While we lived in other worlds, all different worlds and perhaps even different universes entirely, our "past life" originates from here at the Grove, before it became what we know today. What our lives were here doesn't appear to matter much in terms of figuring out how to get back home or how to defeat the creature that inhabits the woods, but this may be subject to change.

There are more guardians outside of the Grove. They're akin to... demigods, in a sense of the world. Not quite gods, not quite human... something greater. Moder and the River Guardian used to be corrupted, though on their deaths seemed to have been cleansed of this corruption. Though, going forward, killing the Guardians to purify them may prove detrimental. We simply got lucky with the first two. They were strong enough to revive. If we try again, we might not have this luck.

Aldric's Manor is a place where Heimr's kids are currently. We can't get it, and they're horrible at listening to us. One of his children... There's a grave outside for her. Do not do anyhting disrespectful by it.
There's a part of the forest where you might find people you know, but as trees. It's very fucked up, I do not recommend going there.
The Garden is where you'll end up if you die. I don't know much about this place, but I know there's a price you'll pay if you end up here, and that Nene brings you back if you do end up here. Do not die. Do not end up here. This is not me asking.
The River is where, unsurprisingly, the River Guardian is. Return any remains of the fish we eat from there back to it after we're able to fish there again. Thank the River Guardian when you take apples from the tree nearby there, and thank Moder when you take berries from the bush near it. Do not take bones from the river without permission.
There's other places within the forest and such, but if you want specifics, talk to Elsword. He has a map.
If you do end up going into the forest, bring a pair of the golden spectacles that Heimr has with you. They will show you a... safe-adjacent way into the forest. It won't guarantee safety, but it'll be your best case scenario.